"Execution of PAC script … failed" on macOS, invalid URL escaping of proxy auto configuration URL

Hi all,

We got a report from a macOS user that they could not get their proxy configuration work.

The error reported was:

[Qt] Execution of PAC script at "http%3A%2F%2Fwpad.example.com%2Fwpad.dat" failed: The operation couldn’t be completed. (NSURLErrorDomain error -1002.)

`scutil --proxy` shows correct PAC URL:

<dictionary> {
ProxyAutoConfigEnable : 1
ProxyAutoConfigURLString : http://wpad.example.com/wpad.dat
}

It looks like the PAC url is incorrectly url-encoded?